Ground working tools or tools that are used to move earth typically have a number of teeth. For example, excavator buckets have a number of teeth at the front edge of the bucket. Augers typically comprise a screw that is rotated by a drive unit. As the screw rotates, it digs into the ground and removes earth to thereby form a hole. In order to increase the efficiency of digging using an auger, the leading edge of the screw is often provided with a number of teeth.
The ground engaging teeth of ground working tools are subject to large loads and high wear. A number of strategies have been developed in order to minimise wear and extend the life of the ground engaging teeth. For example, ground engaging teeth often have a hard facing applied to the ground engaging surfaces thereof. Although this does increase the working life of the ground engaging teeth, ultimately the ground engaging teeth will wear out and will need to be replaced.
It is desirable that replaceable ground engaging teeth be easy to fit to the ground working tool, be firmly retained in place during use of the ground engaging tool and be easily removed once they have worn in order to minimise downtime with the tool. A number of different proposals have been put forward to mount replaceable teeth in ground working tools.
Most ground working tools are provided with one or more tooth holders that hold the replaceable teeth. Each tooth holder may comprise a pocket or a recess. The replaceable tooth can be inserted into the pocket or recess. The pocket or recess of the tooth holder may have an open front and open sides. The tooth is inserted into the tooth holder and retained in place using various mechanisms.
A number of replaceable teeth are held in place using deformable rubber members or resilient inserts. Some examples are shown in U.S. Pat. Nos. 3,359,662, 3,323,235 and Australian patent number 2004203825. In other embodiments, rubber pads are joined to the upper and lower surfaces of the tooth and act to increase the friction between the upper and lower surfaces of the tooth and the facing surfaces of the tooth holder. Other examples utilise a retaining pin that passes through apertures in the tooth holder that come into alignment with an aperture or a notch in the tooth. When the retaining pin is inserted in place, the retaining pin prevents removal of the tooth from the tooth holder. It has been found and that during use of the ground working tool, the tooth can firmly wedge against the retaining pin, thereby making it very difficult to remove the retaining pin when it is time to replace a worn tooth.
Replaceable teeth that are used in augers often comprise a distal end that forms the working surface of the tooth and a proximal end that is in the form of two spaced legs. The tooth holder comprises a recess or a pocket having an upper surface and an opposed lower surface, with a web extending between the upper and lower surfaces. The web is shaped such that it is of complementary shape to the slot formed by the space between the two spaced legs. When the tooth is inserted into the tooth holder, the two legs extend on either side of the central web of the tooth holder. Resilient members, rubber members, and/or retaining pins are then used to retain the replaceable tooth in position.
It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country.